{"product_id":"27-804908a00-gasket-set-lower-unit-kit-for-mercury-8hp-9-9hp-4-stroke-jlm-marine","title":"27-804908A00 Gasket Set Lower Unit Kit for Mercury 8HP 9.9HP 4-Stroke | JLM Marine","description":"\u003ch2\u003e27-804908A00 Gasket Set Lower Unit Kit for Mercury 8HP 9.9HP 4-Stroke | JLM Marine\u003c\/h2\u003e\n\n\u003cp\u003eThis \u003cstrong\u003eLower Unit Gasket Set\u003c\/strong\u003e is engineered to deliver a perfect fit and reliable performance for Mercury 8HP and 9.9HP 4-stroke outboard engines. Designed as a direct replacement for OEM seal kits, it ensures a seamless installation and leak-free operation for your lower unit assembly.\u003c\/p\u003e\n\n\u003cp\u003eThis kit directly replaces Mercury part numbers \u003cstrong\u003e27-804908A00\u003c\/strong\u003e, \u003cstrong\u003e27-8M0082883\u003c\/strong\u003e, \u003cstrong\u003e27-8M0065830\u003c\/strong\u003e, \u003cstrong\u003e27-804908A02\u003c\/strong\u003e, and \u003cstrong\u003e27-8M0060176\u003c\/strong\u003e, providing broad compatibility across multiple Mercury lower unit configurations.\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eComprehensive gasket and seal kit for complete lower unit service\u003c\/li\u003e\n  \u003cli\u003ePrecision-engineered to OE specifications for reliable sealing\u003c\/li\u003e\n  \u003cli\u003eFits Mercury 8\/9.9 HP 4-stroke outboards (serial R042475 \u0026amp; up)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Cross-Reference\u003c\/h2\u003e\n\n\u003cp\u003eUse this table to confirm equivalent part numbers across OEM and aftermarket applications:\u003c\/p\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\" style=\"width:100%; border-collapse:collapse;\"\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eBrand\u003c\/th\u003e\n      \u003cth\u003ePart Number\u003c\/th\u003e\n      \u003cth\u003eNotes\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e27-804908A00\u003c\/td\u003e\n      \u003ctd\u003ePrimary OEM reference\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e27-8M0082883\u003c\/td\u003e\n      \u003ctd\u003eAlternate OEM number\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e27-8M0065830\u003c\/td\u003e\n      \u003ctd\u003eCross-reference\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e27-804908A02\u003c\/td\u003e\n      \u003ctd\u003eCross-reference\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003e27-8M0060176\u003c\/td\u003e\n      \u003ctd\u003eCross-reference\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eCompatible Engine Models\u003c\/h2\u003e\n\n\u003cp\u003eConfirm your engine model\/year in the table below. For Mercury owners, here's a guide to help you identify your engine's serial\/model: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/serial-number-guide\/mercury-outboard-serial-number-guide\" rel=\"nofollow noopener\" target=\"_blank\"\u003eMercury Serial Number Guide\u003c\/a\u003e. You can also review exploded diagrams to verify part numbers: \u003ca href=\"https:\/\/jlmmarine.com\/blogs\/diagrams\/mercury-parts-catalog\" rel=\"nofollow noopener\" target=\"_blank\"\u003eMercury Parts Diagrams \u0026amp; Catalog\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\" style=\"width:100%; border-collapse:collapse;\"\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eBrand\u003c\/th\u003e\n      \u003cth\u003eModel\u003c\/th\u003e\n      \u003cth\u003eRated HP\u003c\/th\u003e\n      \u003cth\u003eStroke\u003c\/th\u003e\n      \u003cth\u003eSerial Range\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eMercury\u003c\/td\u003e\n      \u003ctd\u003eMariner\u003c\/td\u003e\n      \u003ctd\u003e8 \/ 9.9 HP\u003c\/td\u003e\n      \u003ctd\u003e4-Stroke\u003c\/td\u003e\n      \u003ctd\u003eR042475 \u0026amp; Up\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\" style=\"width:100%; border-collapse:collapse;\"\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eSpecification\u003c\/th\u003e\n      \u003cth\u003eValue\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eProduct Type\u003c\/td\u003e\n      \u003ctd\u003eLower Unit Gasket \u0026amp; Seal Kit\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eApplication\u003c\/td\u003e\n      \u003ctd\u003eLower Unit Assembly\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eCompatibility\u003c\/td\u003e\n      \u003ctd\u003eMercury 8HP \/ 9.9HP 4-Stroke Outboards\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eOEM Replacement Numbers\u003c\/td\u003e\n      \u003ctd\u003e27-804908A00, 27-8M0082883, 27-8M0065830, 27-804908A02, 27-8M0060176\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003ePackage Contents\u003c\/h2\u003e\n\n\u003cp\u003eThis kit includes:\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\u003cstrong\u003e1× Lower Unit Seal Gasket Kit\u003c\/strong\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003cspan style=\"color:red;\"\u003eThe package contains all the parts shown in the product picture\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Guide\u003c\/h2\u003e\n\n\u003col\u003e\n  \u003cli\u003eDisconnect the outboard motor from the power source and allow it to cool completely.\u003c\/li\u003e\n  \u003cli\u003eDrain all gear oil from the lower unit into an appropriate container.\u003c\/li\u003e\n  \u003cli\u003eRemove the propeller, then unbolt and separate the lower unit from the mid-section housing.\u003c\/li\u003e\n  \u003cli\u003eCarefully disassemble the lower unit components, noting the position of each seal and gasket.\u003c\/li\u003e\n  \u003cli\u003eClean all mating surfaces thoroughly, removing old gasket material and debris with a scraper and solvent.\u003c\/li\u003e\n  \u003cli\u003eInspect all surfaces for corrosion, warping, or damage that may prevent proper sealing.\u003c\/li\u003e\n  \u003cli\u003eInstall new gaskets and seals from this kit in the exact positions of the originals, ensuring correct orientation.\u003c\/li\u003e\n  \u003cli\u003eApply a thin coat of marine-grade grease to seals to aid installation and prevent damage during assembly.\u003c\/li\u003e\n  \u003cli\u003eReassemble the lower unit components, following your service manual's torque specifications for all fasteners.\u003c\/li\u003e\n  \u003cli\u003eReattach the lower unit to the mid-section, ensuring proper alignment and torquing all mounting bolts to spec.\u003c\/li\u003e\n  \u003cli\u003eRefill the lower unit with the manufacturer-recommended gear oil through the fill port until it reaches the vent hole.\u003c\/li\u003e\n  \u003cli\u003eReinstall the propeller, run the engine briefly, then recheck the gear oil level and inspect for leaks.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How do I confirm this gasket set fits my Mercury outboard?\u003c\/strong\u003e\u003cbr\u003e\nA: Check your engine's serial number (located on the mounting bracket) and confirm it is R042475 or higher for 8HP\/9.9HP 4-stroke models. Cross-reference your current part number against the five OEM numbers listed above to ensure compatibility.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How often should I replace the lower unit gaskets and seals?\u003c\/strong\u003e\u003cbr\u003e\nA: Replace gaskets and seals whenever you perform lower unit service, disassembly for propeller shaft work, or if you notice gear oil leaks or milky oil indicating water intrusion. Most manufacturers recommend lower unit service every 100 hours or annually.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: What are the signs that my lower unit seals have failed?\u003c\/strong\u003e\u003cbr\u003e\nA: Common symptoms include gear oil that appears milky (water contamination), visible oil leaks around the lower unit housing, difficulty shifting gears, unusual noise from the gearcase, or rapid gear oil loss between service intervals.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: Can I reuse the old gaskets if they look intact?\u003c\/strong\u003e\u003cbr\u003e\nA: No, gaskets are designed for single use only. Even if they appear undamaged, they compress during initial installation and will not seal properly when reused, leading to leaks and potential water intrusion into the lower unit.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: Do I need any special tools to install this gasket set?\u003c\/strong\u003e\u003cbr\u003e\nA: You'll need basic hand tools (sockets, wrenches, screwdrivers), a torque wrench, gasket scraper, marine-grade grease, and the appropriate gear oil. A service manual for your specific engine model is highly recommended for proper torque specifications and assembly procedures.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: What's the difference between OEM and aftermarket gasket sets?\u003c\/strong\u003e\u003cbr\u003e\nA: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How fast do you ship and how much does it cost?\u003c\/strong\u003e\u003cbr\u003e\nA: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: What is your warranty and return policy?\u003c\/strong\u003e\u003cbr\u003e\nA: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused \u0026amp; in original condition); please see our policy page or reach out for instructions.\u003c\/p\u003e\n\n\u003ch2\u003eImportant Notes\u003c\/h2\u003e\n\n\u003cul\u003e\n  \u003cli\u003eVerify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.\u003c\/li\u003e\n  \u003cli\u003eThis product is an aftermarket replacement part and is not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended to ensure safety and optimal performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Choose JLM MARINE?\u003c\/h2\u003e\n\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eQuality Assured:\u003c\/strong\u003e As a trusted manufacturer for over 20 years, we supply top marine brands globally.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFast Global Shipping:\u003c\/strong\u003e Free delivery worldwide in 5–15 days.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDirect from Manufacturer:\u003c\/strong\u003e Competitive pricing without compromising quality.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"JLM Marine","offers":[{"title":"Default Title","offer_id":51981022200121,"sku":"24MSK720","price":55.09,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0885\/0433\/6697\/files\/12_fa8ac7ce-6896-457b-8994-ad87947b5e07.jpg?v=1772414732","url":"https:\/\/jlmmarine.com\/products\/27-804908a00-gasket-set-lower-unit-kit-for-mercury-8hp-9-9hp-4-stroke-jlm-marine","provider":"JLM Marine Boat Parts Limited","version":"1.0","type":"link"}